Conventional telescopic doors for elevators are basically composed of a metallic frame where a series of main subassemblies are assembled:
Two parallel tracks; PA0 A door panel hanger support equipped with rollers and counter-rollers; and PA0 More or less complex door profiles or panels for fire labyrinth needs. PA0 1. Use of a single track for both high-speed and low-speed door panels. PA0 2. Use of a very simple rolling package with a very stiff construction avoiding the need of any adjustment. PA0 3. Soundproof and fireproof door panel composed of a single steel sheet profile to which a sound absorbing device is added. PA0 4. Dismountable frame with active elements preassembled for a compact and easy transport from factory to the field with minimum manufacturing and erection time.
Most of the conventional solutions in this type of door use two tracks and even at times a solid double track form on which the respective displacement roller and counter-roller form a complete unit. Thus adjustment thereof is difficult to attain because a large number of pieces have to be put in place and adjusted. Likewise, the structural lintel of the door unit has to be effected in such a way that it provides two or three different flat references in order to fasten the two tracks with the corresponding separators and screws.
This type of configuration likewise gives rise to problems of parallelism and straightness of the two tracks plus the cited lintel.
On the other hand, the functioning is likewise negatively affected by the cantilevered configuration of the roller and counter-roller that require very strong shafts and hanger supports to overcome the deformation produced by overhanging doors during reopening.
It should also be taken into account that in conventional doors the panel always has the tendency to be noisy and resonant during movement of the door and in most cases a welded sandwich configuration is necessary to overcome resonance, and sometimes special noise absorbing paint or materials have to be added.
Consequently, depending on the structures of doors for conventional elevators, the main problems reside in cost and quality due to the large number of separate elements, as well as the precision required to obtain parallel smooth movement of the telescopic elements and to the noise produced during operation thereof.
Normally, if the product has to be competitive from the cost point of view, the elements are too weak, giving rise to problems of noise, jerks and wear and tear of the panel surfaces, with regard to the horizontal scratches produced by undesired contacts between moveable parts.
Finally, it should be said that the assembly of this type of door requires a long time to effect the assembly and adjustment of the different elements, which increases the cost and what is more important the cost of maintenance.